Heat exchanger



May 5, 1942 c. B. DALZELL 2,281,754

HEAT EXCHANGER Filed Jan. 27, 1957 4 Sheets-Sheet l Il v C ttf... .J

2 NTOR ATTORNEYS May 5', 1942. c. B. DALZELL HEATEXCHANGER Filed Jan. 27, 1957 4 Sheets-Sheet 2 mvENToR f6/Jgd W M14/ww ATTORNEYS n 0&0- 0 ma@ o @um @@@QQQGQQOGQQQQ @QQ n.. 0 o Q o Q Q Q QQQQOQQQQQQQGQQ@ ,..mhw- A.

May 5, 1942. c. B. DALzELL.

HEAT EXCHANGER Filed Jan. 27, 193'? 4 Sheets-Sheet 3 mvENToR V afval/2.

.ATTORNEYS MM5 1942 I c. B. DALZELL.

HEAT EXCHANGER Filed Jan. 27, 1937 4 Sheets-Sheet 4 'I Z g INVENTOR ATTORNEYS Patented May 5, 1942 HEAT EXCHANGER i Charles B. Dalzell, Little Falls, Cherry-Burrell Corporation,

corporation N. Y., assignor to Chicago, lIll., a

Application January 27, 1937, Serial No. 122,597

2 Claims.

This invention relates to that type of plate heat exchangers for fluids which usually comprise a plurality of heat conducting or heat transfer plates assembled in spaced face to face relation in' a manner to provide shallow fluid flow spaces which are separated by the plates and are connected with circulating passages or connections so that different fluid streams can be circulated in contact with opposite sides of the plates for the exchange of heat from one fluid or stream to another. The heat transfer plates or elements of such apparatus with interposed sealing means bounding the flow'spaces between the adjacent plates or elements are usually separably clamped together so as to enable the separation of the plates for cleaning, and by different groupings or combinations of the plates and circulating connections, heat exchangers adapted for different purposes or uses may be provided. The primary object of this invention is to improve the heat transfer elements of heat exchangers of this type so as to compel a high degree of turbulence in the fluid media and to increase the heat exchange eiciency of such''s,

devices.

Other objects of this invention are to provide novel heat transfer elements by which all portions of the fluid flowing through the flow space between the elements must follow long, tortuous paths and be subjected to active turbulence throughout their path of travel; by which the fluid flows through courses or channels of varying cross section which vary the velocities of different portions of the fluid at the same capacity, and thereby cooperate'with the changes in direction of the portions of the fluid in producing active turbulence therein; which greatly increase the area of the heat exchange surface;

' which are of a formation to function effectively to limit the deflection of the plate elements due to unbalanced fluid pressures thereon; in which the formation of the elements enables them to be made of thinner material and thus further increases the heat transfer emciency and capacity of a heat exchanger of a given size; which, although being of a novel form that insures great turbulence in the fluid and heat transfer efficiency, nevertheless enables-,ready andr thorough cleaning of the elements; and also to provide a heat exchanger having the other features of improvement hereinafter described and set forth in the claims.

In the accompanying drawings:

, element reversed end for end.

Fig. 6 is an elevation on a still larger scale, of an end portion of the element shown in Fig. 4'.

Fig. 'I is a vertical, sectional elevation, enlarged, through a group of the elements on line 1 1, Fig. 4.

Fig. 8 vis a fragmentary, horizontal, sectional view similar to Fig. 3,'but on a larger scale.

' Fig. 9 is 'a section through three of the elements on an enlarged scale on line 9 9, Fig. 6.

Fig. A10 is "an enlarged fragmentary section -fthroiigh three of the elements showing the formation of the seating grooves therein for the gaskets that seal the flow spaces between the elements.

Fig. 11 is a fragmentary elevation of a heat transfer element having a modified arrangement of bosses.

Fig. 12 is a similar view of another modification in which the heat exchange element is provided with bosses on its opposite faces.

Fig. 13 is a transverse section on line I3 l3, Fig. 12, of three adjacent elements having the bosses on their opposite faces.

As illustrated in the drawings, the heat exchanger comprises the usual plurality of heat transfer plates or elements arranged in face to face relation, with interposed compressible space sealing means, in a suitable press or apparatus by which the plates are pressed towards each other, whereby sealed flow spaces are formed between the plates or elements for the flow of fluids or fluid streams to effect the exchange of heat from one fluid or stream to another.

Referring first to the embodiment of the invention shown in Figs. 1 to l0, each of the heat transfer plates or elements Il consists of a relatively'thin plate of material having suitable heat conductivity formed to provide on one face of a plate a multiplicity of spaced apart protuberances, bosses or knobs I2, and cavities I3 in the opposite face of the plate. Preferably, the element is formed from a metal sheet or plate Fig. l is a side elevation of the heat exchanger stamped or embossed to provide spaced concav0- convex portions which form the bosses I2 on one face oi the plate and the cavities I3 in the opposite face of the plate. The bosses shown are of hollow, segmental spherical shape, which is their preferred shape, but they could be made of oval or other shape providing rounded bosses on one face of the plate and rounded cavities in the opposite face of the plate. These bosses are spaced apart both longitudinally and transversely of the plate and are preferably arranged staggered in transverse rows I4, i. e. with the bosses in each transverse row disposed opposite the spaces between the bosses in the next row. Also, preferably the bosses are located non-symmetrically with reference to the longitudinal. central line of the plate so that when the plate is in the position shown in Fig. 4, the bosses will be offset to one side relatively to said central line, whereas if the plate is reversed end for end, the bosses will be offset to the opposite side relatively -to said line, as shown in Fig. 5. This non-symmetrical arrangement of the bosses enables all of the plates to be made alike',- or by the same dies and, by assembling them face to face, with adjacent plates reversed end for end, the bosses on one plate will not register with those on the next adjacent plate, but will be disposed opposite the flat portions between the bosses of said next plate, as indicated by the full and broken lines in Fig. 2, and as shown in the sectional views, Figs. 3 and 8. While this non-symmetrical arrangement is not essential, since the same result could be gained by making the plates of two different forms, it is preferred, as it is obviously more economical to have all of the plates alike and capable of production by the same dies.

In assembling the plates II for use, they are all placed to face the same way or with the bosses projecting in the same direction from the several plates, so that the bosses project from each plate toward the reverse face of the next adjacent plate. In this way the bosses on one plate project into the fluid ilow space between this plate and the next one and act as banles forming numerous tortuous or zig-zag courses through which the iiuid must flow intermittently dividing and subsequently rejoinlng the various ow streams, thereby causing turbulence, change of direction of ilow and a more uniform distribution over the entire heat exchange surface. Such arrangement will prevent the fluid from flowing only overa small portion of the plates intermediate the inlet and outlet openings, and these tortuous courses vary or increase and decrease repeatedly in cross section both lengthwise and sidewise of the plates and also V-transversely to the planes of the plates, the deepest portions of the courses transversely to said planes being at the points where the deepest central portions of the cavities I3 in one plate are opposite the spaces I3a between the bosses on the next plate (see Fig. 8). Thus, the velocity of the fluid ilowing through 'each course is repeatedly increased and decreased as the fluid passes through the flow space from inlet to outlet.

The spaces between the plates II can be sealed at their margins to form coniined iiuid flow spaces and can be connected with circulating passages or connections so as to adapt iluids or iluid streams of different temperatures to ilow through the spaces at opposite sides of each transfer plate for exchangev of heat from one stream or iluld to the other, in any suitable way. the embossed formation of the plates as described, not being necessarily restricted to the arrangement or connections for effecting the desired relations of iiow oi' the dinerent iiuids or streams through the apparatus.

For example, the plates II may be constructed and arranged in this regard in a manner similar to that disclosed in U. S. Patent Nol'- 2,039,216, issued April 28, 1936. to H. Feldmeler, assignor to Cherry-Burrell Corporation, in which, as fully explained in said patent, each plate is provided with two holes passing therethrough and'with sealing gaskets seated in grooves in the plate and engaging the next plate in a Way to eiiect the ilow of different fluids or fluid streams through the ilow spaces at opposite sides of each plate.

In the preferred construction, however, each plate I I is formed at its marginal portions around or outside of the embossed main body portion of the plate with grooves in which is seated a gasket adapted to be compressed between the plate carrying the gasket'and the adjacent plate for sealing the :dow space between the plates and the nuid inlet and outlet holesor passages therefor. As shown. the plate is providedwith a marginal gasket groove I5 which extends along the side edges and end portions of the plateand, in addition. is provided with circular grooves I6 at the four corners of the plate which merge into the marginal groove I5. and also with grooves I1 which extend diagonally acrossthe corner portions of the plate from the side to the end portions of the 'marginal groove I 5 between the central embossed portion of the plate and the circular corner grooves. A sealing gasket I8 is seated in these grooves, this gasket having portions occupying the endless marginal groove I5 and also the circular corner and diagonal portions of the grooves. l

As explained in said Feldmeier patent, the flow space between each two plates communicates through interruptions or gaps I9 and 20 (Figs. 4-6) in the diagonal and circular gasket portions 20a and 2| -at one end of one plate with a hole or passage 22 through this plate, and communicates through corresponding interruptions or gaps 20a and 2I in the gasket at the opposite end of the plate with a hole or passage 23 through the next plate, so that fluid will ilow through the sealed iiow space from an inlet at one end thereof to an outlet at its opposite end. Thus, a

yliquid entering the flow space between adjacent plates iiows lengthwise therethrough, and by reason oi' the bosses projecting into the ow space, the body of liquid is broken up into numerous streams or portions, each of which is -baiiled back and forth by the bosses and caused to follow a long, tortuous course from the inlet to the outlet of the iiow space with the results herein explained.

Ii' the gasket grooves had any considerabledepth, then the pressure of the adjacent plate against the elastic or rubber gasket would tend to widen the grooves, due to the compression of the gasket, because this considerable pressure would bend the metal along the juncture of the side walls with the bottom walls of the grooves. Therefore, the grooves are preferably made as shallow as is consistent with proper seating and retention of the gasket in the grooves. For best results, the grooves should not be substantially deeper than indicated in Fig. 10 of the drawings, from which it will be seen that the radial centers of the curved corners joining the side and bottom walls of the grooves are in the same plane as the centers of the curved corners joining the side walls of the groove to the normal portion of the flow spaces because, if these dimensions were the plate. By thus forming the gasket grooves, the plate can be stamped from sheet metal of relatively thin gage without the necessity for any means for bracing or reinforcing the walls of the grooves. A

ABy reason of the described form and relative arrangement of the bosses i2, they cause a high degree of turbulence` in the fluid media going through the exchanger, thus bringing all particles thereof into contact with a heat exchange surface a great many times during their passage through any flow space between two'plates or elements. Since the bosses o n one plate are opposite and extend close to the fiat or normal surface portions of the adjacent plate, and are staggered relativelyto the cavities in the latter plate, the tortuous courses or channels thus formed for the media vary in cross section at successive points throughout their lengths and the consequent varying velocities in different portions of the flowing media further augment the turbulence therein. Furthermore, each portion of.

the huid medium is.forced, to take a long path in flowing through a flow space from the inlet to the outlet. Considering, for instance, a particle of the medium as entering the ow space. it cannot go directly `from the inlet to the outlet because it immediately encounters one of the bosses, which it must go around in order to continue its way, when it runs into another particle,

the path of which has been deflected by one of the bosses. ,These two particles in their endeavor to take the same path produce immediate turbulence because of the varying velocities, due to the varying cross section of the flow courses. A uniform distribution of the medium over the heat exchange surfaces results. Instead of followingsome predetermined short path through the flow space, the particles are banled or zigzagged about, going across the plate and back, so

that their actual path through the flow space is always considerably longer than the direct distance from inlet to outlet. Also, the bosses increase the area of the'heat exchange surface from the normal projected area thereof by a percentage dependent upon the number, diameter and depth of the bosses. With the bosses proportioned and spaced as shown in the drawings, the heat exchange surface is increased approximately twenty percent.

In addition to effecting turbulence and increasing the area of heat exchange surface, the bosses, as shown, serve to support and limit deflection of the heat transfer plates due to unbalanced fluid pressures thereon. The pressures on the plates are rarely balanced. With a series of plates used as a regenerator, for instance, where the rate of ow of two liquid streams is the same both ways, there would be a maximum pressure difference at each end of the series and a balanced pressure at the middle. It is therefore desirable to limit deflection of the plates, due to this unbalanced pressure, because deflection of a plate not only is liable to cause leakage around the gaskets. but it also varies the thickness of the flow space so that the relative velocities of the fluids are affected, with consequent effect in the turbulence and, therefore, in the heat exchange efllciency of the device. By

making the bosses uniformly of a height approximately equal to the thickness of the flow space. deflection of the plates is effectively limited throughout the whole area of the embossed body portions of the plates. The height of the bosses should be somewhat less than the thickness of the same, the' bosses of one plate would contact with thev flat normal surface ofthe adjacent plate and prevent the proper sealing action of the gaskets. When the plates are squeezed up to give the proper flow space thickness, the bosses still should be short of striking the flatv surface of the next plate by a small amount, say, for example, about loo of an inch, or an amount insuillcient-to permit an objectionable -exing of `the plates. Such uniform height of the bosses' is an advantage, since the plates are thus properly supported throughout the area of their embossed body portions. This also permits the use of thinner material for the plates so as to further increase their heat transfer efficiency.

The relative proportions, shape and A spacing of the bosses can be varied within the scope of my invention. While the heat elciency and turbulence are increased by reducing the diamef` ter and spacing of the bosses, nevertheless they should be of sufficient size and spacing to enable ready and thorough cleaning of both surl faces of the plates. The bosses relatively proportioned and space substantially as shown in the drawings, that is, with bosses about 3/4 of an inch in diameter by 1/4 of an inch deep and on 1 inch centers have been found by experiment to give` 'a high rate of heat transfer and surfaces which are practical to clean.

,The-plates il are als'o` shown as formed with knobs i2a in adjacent rows both lengthwise and crosswise of the element or plate I ia are disposed opposite each other instead of being staggered, as shown in Figs. 2 to l0. This arrangement of the bosses will produce fair turbulence of the liquid and fair heat transfer. In relation to the flow of liquid diagonally from inlet to outlet at diagonally. opposite corners of the plate, the bosses are still in staggered relation and, although the liquid might tend to follow a straighter course through the flow space, it still would be influenced by the tortuous courses formed by the bosses and by the varying cross section of different portions of the courses. Therefore. this modified arrangement will effect turbulent flow and heat transfer even though it may be to a lesser degree than in the hereinbefore described construction. Except as to this different disposition of the bosses, the plate may be as before described.

As shown in Figs. 12 and 13, each plate orelement Il b is formed with hollow or concavo-convex bosses or knobs |217 on bothI of its opposite sides or faces. In this form of the plate, as shown. the bosses projecting from o ne face are disposed between the bosses projecting from the opposite face of the plate as regards the longitudinal and transverse rows of the bosses. It will be clear from Figs. l2' and 13 that this formation of these plates will give similar results to the first described construction so far as the tortuous courses or passages and the varying cross section of the diilerent portions of the courses are concerned by having the knobs and corresponding cavities on both sides of the plate.

The broken line circles llc and I2d in Fig. 12 indicate the relative positions of the knobs and cavities of adjacent Vplates and show that by 'non-symmetrical location of the -knobs on the formed or constructed as herein disclosed gives.

the following improved results and advantages: The heat transfer elements of heat exchangers of this type are improved so as to more eiectively utilize all of their available heat exchange surface, as well as to compel a more uniform distribution and a higher degree of turbulence in the fluid media in heatexchange relation, thus causing an increase in the overall heat exchange efliciency of such a device.

A heat transfer element is provided having a multiplicity of appropriately spaced protuberances projecting into the flow space denlng therein flow passages of radically varying cross sections thereby preventing smooth or streamline flow of the fluid and causing violent turbulence.

The heat transfer element has a multiplicity of protuberances which are so spaced as to constitute effective baiiles and directional guides for the fluid passing through the flow space, resulting in the intermingling and redivision of the streams in the various flow passages causing turbulence and a more uniform distribution of the fluids in effective heat exchange relation over the entire available heat exchange surface within the flow space. s

A heat exchange element is provided having a multiplicity of hollow protuberances so placed in spaced relation upon the various heat'transfer elements that the combination of the outer walls of the protuberances and the adjoining surface of the adjacent plate forms constrlcted ow passages from which the fluid is led into rapidly expanding flow passages formed by the space between the flat surface of the first plate and the hollow space below a protuberance in the adjacent-plate. Such radical changes of cross section of the flow passage results. in violent three dimensional turbulence and improved distribution of the media overthe heat exchange surfaces. y

The heat exchange element has protuberances which are `positioned on the element so that they are capable of limiting the effect of deilec- ,tion of the heat transfer elements on the effective capacity of the flow space, as well as to aid in the support of yadjacent plates.-

- 'I'he heatl transfervplate -has a gasket groove that will not upon compression of the gasket become distorted or distort the heat transfer plate or require stiiening members.

I claim as my invention:

l; A heat exchange element for plate heat exchangers of the character described, consisting of a heat conducting plate formed with a multiplicity of relatively closely spaced but separated concavo-convex portions forming knoblike bosses on one face ofthe plate and cavities in the opposite face of the plate, said bosses being staggered both longitudinally and transversely of the plate and being arranged non-'symmetrically relatively to a central line of the plate so that when the plate is reversed end for end in the plane of the plate beside a similar plate the bosses of one plate will be out of register with the cavities and bosses of the adjacent plate.

2. A heat exchanger for fluids comprising separate heat transfer plates separately secured in spaced face to face relation with interposed sealing means to form separate sealed uid `flow spaces at opposite sides of each plate, each said plate formed with a multiplicity of separated concavo-convex segmental globular portions forming alternating 'bosses and cavities-on both opposite faces of the plate, said bosses and cavities being arranged in staggered relation both longitudinally and transversely of the plate, and the bosses and cavities of adjacent plates be'- ing out of register.

CHARLES B. DALZELL.

CERTIFICATE CF CORRECTION. Patent No. 2,281,751T. may 5, 191m.

CHARLES B. DALz'ELL.

-It is hereby certified that error appears in the printed specification' of the Yabove numbered patentrequiring correction as follows: Page 5, second column, line 2.5, for the word "space"y read f-spaced--f line- )4.0, for

"of" read -or; page b., second column, line 5h, claim 2, for'the word "separately" read separably; and that the said Letters Patent should be read with this Correction therein that the same may conform to the rec.-

ord of the case in the Patent Office.

signed end sealed this 15th dey ef september, A. D. 19h2.

, Henry Van Arsdale, (Seal) Acting Ccnmissioner of Patents. 

